'Growth' has been defined as permanent and irreversible increase in dimensions. The size of a plant, though depending in various ways on external conditions is a specific character. The rate of growth, (i. e. the enlargement of cells as well as the form-ation of primordia of new organs) does by no means proceed at a uniform pace even when external conditions are constant. The three phases involved in growth are (1) the formative phase, (2) the phase of enlargement, and (3) the phase of maturation. The formative phase is mainly concerned with meristamatic activity. Cell-division proceeds actively and the primodia of new organs are laid down. Increase in size is the characteristic of the phase of enlargement. The cells increase in size and the primordia of new organs undergo zonal differentiation. The increase in the height of the paddy plant is really the cumulative effect of a number of cells undergoing the enlargment phase in different regions of the plant. The phase of maturation or ripening is the final phase of growth. This starts when enlargement has practically ceased.
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